Van Gaal has been impressed with the England striker's approach since taking over at Old Trafford earlier this summer and believes he will give his heart and soul to his new role.
"For me, it's always very important, the choice of captain," the Dutchman said in quotes posted on United's website after Tuesday evening's 2-1 pre-season friendly win over Valencia.
"Wayne has shown a great attitude towards everything he does. I have been very impressed by his professionalism and his attitude to training and to my philosophy. He is a great inspiration to the younger members of the team and I believe he will put his heart and soul into his captaincy role."
Rooney spoke earlier this year of his ambition to skipper both United and England.
"It is a huge honour for me - and for my family - to be named captain of this great club," the former Everton forward said.
"It is a role I will perform with great pride. Team spirit has always been very high in our dressing room and I am very grateful to the manager for the faith he has shown in me.
"I look forward to leading the team out on Saturday at our first match of the new season."
Darren Fletcher has been appointed United vice-captain, with Van Gaal acclaiming the Scot as a "natural leader".
"I am delighted to have been named as vice-captain," Fletcher said. "It's a very proud moment for me and my family. Wayne and I have always worked well together and we will continue to work closely together in our new roles. I would like to thank the manager for putting his trust in me."
Van Gaal added: "Darren is a natural leader and will captain the team when Wayne isn't playing. Darren is a very experienced player and a very popular member of the dressing room, I know he will work well alongside Wayne."
- Sports & Recreation
- Van Gaal